In the past, motorized saws were conventionally not braked after a given cutting operation. However, more recently as part of a drive to increase safety in industry, investigation of the problem of braking such blades after cutting was begun. Most recent attempts at braking the rotation of saws has usually been to use the approach of dynamically braking the blade, i.e., reversing the phase of the electrical impulses to the saw motor, to thereby electrically restrain further rotational movement of the saw blade attached thereto. However, this method precludes the use of a screw-on type of attachment between the saw motor and the blade since such braking would create forces that may cause the blade to unscrew from the motor shaft. It is also an unsatisfactory method since a large amount of power would be needed to stop the blade's movement with any degree of speed.
Another aspect of the braking problem concerns the size constraints involved in placing a brake apparatus external to the saw motor. Such an apparatus must be small enough not to be a limiting factor on the width of a given wood member to be cut by the saw blade. Thus, it was found that a disc brake system was inappropriate due to the fact that to make the brake disc size small enough to not limit the width of the wood member to be cut, the pad surface area available for the disc brake was too small. Testing the operation with such a brake, it was found that the disc pads wore very quickly, and were inefficient in quickly reducing saw blade rotation.
A third problem in adding a brake apparatus external to a drive motor is the problem of coupling the brake apparatus to the drive shaft and the blade. Conventional means for coupling would include a plurality of setscrews to hold the brake apparatus to the drive shaft. However, with this method there would be much more of a tendency for the setscrews to shear, due to the high stress experienced when braking of saw blade rotation is done quickly.